The present invention is directed to a disconnect coupling, and more specifically, to an improved apparatus for retaining a male portion of a disconnect coupling within a bore of a female portion of a disconnect coupling.
Disconnect couplings, commonly referred to as quick-disconnect couplings, are highly desirable for use in both hydraulic and pneumatic applications. Furthermore, in certain specialized applications it is essential that a quick disconnect coupling be capable of withstanding extremely high pressures in the lines being connected through the coupling. In hydraulic applications, for example, it is possible for the pressures applied to a coupling to exceed 60,000 pounds per square inch.
The state of the art disconnect coupling utilizes a plurality of generally spherical ball bearings secured within the female portion of the coupling that are releaseably received in a retaining groove formed in a male portion of the disconnect coupling to securely retain the male portion of the coupling within the female portion of the coupling. This type of disconnect coupling functions acceptably where moderate pressures are applied across the disconnect coupling. However, under higher pressures ball bearing type disconnect couplings can fail due to deformation of the bearing surfaces within the retaining groove in the male portion of the coupling. Because the spherical ball bearings of this type of coupling contact the bearing surface of the retaining groove in the male portion of the coupling at a very small area which can almost be characterized as a single point, these ball bearings will subject the bearing surface of the retaining groove to point stresses which regularly exceed the ultimate strength of the material of the male portion of the coupling. Deformation of the bearing surface of the retaining groove makes it more likely that the male and female portions of the coupling will fail to properly engage one another. In addition, ball bearings in ball bearing type disconnect couplings tend to translate a disproportionately large amount of the longitudinal forces applied across the ball bearings and retaining groove into radial forces directed in a normal direction relative to the longitudinal axis of the coupling and applied to the female portion of the disconnect coupling. Repeated application of these radially outwardly directed forces to the female portion of the coupling may deform or even shatter the female portion of the coupling.
One solution to the problems associated with ball bearing type disconnect couplings presently on the market, has been the utilization of a female portion having a retaining means with a curved surface which contacts the bearing surface in the retaining groove on the male portion. of the coupling along an arc. Increasing the amount of contact between the retaining means and the bearing surface of the retaining groove of the male portion of the coupling helps to decrease the magnitude of the stresses applied to the bearing surface of the male portion. However, the area of contact is a line and is still relatively small; therefore the stresses applied to the bearing surfaces can exceed the ultimate strength of the material from which the bearing surface of the male portion is fabricated. In addition, the curved surface of the retaining means, like the curved surface of the ball bearing, directs an unacceptably high amount of force in an outward radial direction into the female portion of the coupling.
Therefore, it is an object of the invention to provide a structure for a retaining mechanism that will impart substantially lower stresses to the bearing surfaces of the male portion of the coupling. It is also an objective of the present invention to provide a structure for a retaining mechanism which minimizes the magnitude of the radial forces applied to the female portion of the coupling. A last objective of the present invention is to provide a structure for a retaining mechanism having a large cross-sectional area for resisting shear stresses and which is capable of evenly distributing applied shear stresses around the bearing surfaces of the retaining groove of the male portion of the coupling.
The present invention comprises a disconnect coupling that is connectable to high pressure fluidic lines. The coupling of the present invention has a female portion with a means for connecting it to a fluidic line. The female portion has a housing with a longitudinal axis and a fluid flow channel formed therethrough along the longitudinal axis. The coupling also has a male portion which also has means for connecting it to a fluidic line. The male portion of the coupling is receivable within the channel of the female portion. In addition, the male portion has a fluid flow passage formed therethrough along a longitudinal axis, with the passage positioned so as to communicate with the channel of the female portion when the male and female portions are connected.
A retaining mechanism for quickly connecting and disconnecting the male and female portions is provided and comprises a plurality of retaining lugs that are moveably mounted within the housing of the female portion so as to be capable of engaging the male portion of the coupling. The retaining lugs are slidably movable between a locking position, wherein the lugs extend within the channel to engage the male portion, and a release position, wherein the lugs are substantially retracted within the housing of the female portion so as to permit placement or removal of the male portion of the coupling in or from the channel of the female portion of the coupling.
A retaining groove is formed around the male portion and is positioned so as to receive the retaining lugs when the male portion is connected to the female portion and the lugs are in their locking position. Of importance here is that both the retaining groove and the retaining lugs have bearing surfaces that are congruent to one another. A collar is slidably mounted on the female portion of the coupling and is moveable between a first position, wherein the collar lockably maintains the retaining lugs in their locking position, and a second position wherein the collar permits the retaining lugs to be moved to their release position.
It is preferred that the bearing surfaces of the retaining lug and of the retaining groove have substantially the same surface geometry as a frustum of a right circular cone. In this case, the right circular cone which defines the bearing surfaces of the preferably annular retaining groove and the retaining lugs has an axis of symmetry that coincides with the longitudinal axes of the female and male portions of the coupling. The shape of the respective bearing surfaces of the retaining lugs and retaining groove permits substantially full facial contact therebetween when the male and female portions of the coupling are connected and the retaining lugs are lockably retained in the retaining groove by the collar.
The retaining lug of the present invention has a body with a tip and a base, with the base being received within the female portion of the disconnect fluid coupling. The tip of the retaining lug has at least one bearing surface formed thereon, with the bearing surface being arranged and constructed to mate with a congruent bearing surface that is formed in male portion of the disconnect fluid coupling. The respective bearing surfaces of the tip of the retaining lug and the male portion of the coupling define an area of contact that has a substantial surface area.
The inner and outer bearing surfaces of the retaining lug are inclined at an angle of no more than 30 degrees as measured from a plane perpendicular to the longitudinal axis of the disconnect coupling. Preferably the inner and outer bearing surfaces of the retaining lug are angled at approximately 20 degrees as measured from a plane perpendicular to the longitudinal axis of the disconnect coupling.
The retaining lug according to the present invention takes the shape of a radial section of a right cylinder and preferably has bearing surfaces that have the geometric shape of the surface of a section of a frustum of a right circular cone. The base the retaining lug generally also has a lip formed thereto which prevents the lug from sliding into the channel of the female portion of the disconnect fluid coupling. Each retaining lug may span between 30 and 60 degrees of the circumference of the annular bearing surface of the retaining groove. However, it is preferred that the retaining lugs span no more than 45 degrees of the circumference of the channel of the housing of the female portion. Furthermore, it is also preferred that each lug have at least one bearing surface that is at least 0.1 square inches in area.
These and other objectives and advantages of the present invention will become apparent from the following detailed description and illustrative drawings when read in conjunction with the appended claims.